sort local interfaces before selecting one

src/bin/fullnode-config.rs

@@ -7,12 +7,14 @@ extern crate solana;
 use clap::{App, Arg};
 use solana::crdt::FULLNODE_PORT_RANGE;
 use solana::fullnode::Config;
+use solana::logger;
 use solana::netutil::{get_ip_addr, get_public_ip_addr, parse_port_or_addr};
 use solana::signature::read_pkcs8;
 use std::io;
 use std::net::SocketAddr;
 
 fn main() {
+    logger::setup();
     let matches = App::new("fullnode-config")
         .version(crate_version!())
         .arg(

src/netutil.rs

@@ -49,14 +49,36 @@ pub fn parse_port_or_addr(optstr: Option<&str>, default_port: u16) -> SocketAddr
 }
 
 pub fn get_ip_addr() -> Option<IpAddr> {
-    for iface in datalink::interfaces() {
+    let mut ifaces = datalink::interfaces();
+
+    // put eth0 and wifi0, etc. up front of our list of candidates
+    ifaces.sort_by(|a, b| {
+        a.name
+            .chars()
+            .last()
+            .unwrap()
+            .cmp(&b.name.chars().last().unwrap())
+    });
+
+    for iface in ifaces {
         for p in iface.ips {
-            if !p.ip().is_loopback() && !p.ip().is_multicast() {
+            trace!("get_ip_addr considering iface {} {}", iface.name, p);
+            if p.ip().is_loopback() {
+                trace!("    loopback");
+                continue;
+            }
+            if p.ip().is_multicast() {
+                trace!("    multicast");
+                continue;
+            }
             match p.ip() {
                 IpAddr::V4(addr) => {
-                        if !addr.is_link_local() {
+                    if addr.is_link_local() {
-                            return Some(p.ip());
+                        trace!("    link local");
+                        continue;
                     }
+                    trace!("    using ==> {}", p.ip());
+                    return Some(p.ip());
                 }
                 IpAddr::V6(_addr) => {
                     // Select an ipv6 address if the config is selected
@@ -68,7 +90,6 @@ pub fn get_ip_addr() -> Option<IpAddr> {
             }
         }
     }
-    }
     None
 }